Offset or lithographic printing presses have been in common use for many years. Indeed, the A.B. Dick printing presses, models 360 and 9800 series with chain delivery are perhaps the most common presses in use. These presses include an upper plate cylinder, a blanket cylinder and a lower impression cylinder. The blanket cylinder is a shell cylinder; that is, it is formed of an outer cylinder wall or shell with an inner central axle shaft. Radial lugs connect the shell to the inner shaft. The blanket cylinder is relatively expensive and the shell can be deformed upon excessive weight bearing or use. The present invention provides a perforated scoring adapter bar which readily and easily fits onto the blanket cylinder. Installation does not require disassembly of the printing press in any way and the job is inexpensively and easily accomplished. Moreover, the disclosed perforating and scoring adapter bar does not place undue stress or wear upon the blanket cylinder and all stresses are borne by the sturdy blanket cylinder axle shaft, rather than by the more easily damaged cylindrical shell.